Electronic switching electric motor

ABSTRACT

An electronic switching electric motor having a rotor and a stator having a number of stator teeth is characterized in that an assembly element of stator teeth is made of plastic and is co-molded with the stator teeth. The electric motor has two support seats for the rotor, where at least one of the support seats is present in the assembly element.

The present invention refers to an electronic switching electric motor.

In particular, the present invention refers to, without in any waylosing any of its generality, an electronic switching electric motorwhich may be used to advantage for activating ventilation devices to beinstalled in refrigerators, and comprises a stator, and a rotor which isrotatably coupled to the stator itself, and an electronic device forsupplying and controlling the electric motor itself.

Normally, in electronic switching electric motors of well-known types,the above-mentioned stator comprises a determined number of statorteeth, a determined number of windings realised around the teeththemselves, and an assembly element of the teeth themselves realised ininsulating plastic material to insulate the windings one form the otherand from the stator teeth themselves.

With regard to well-known types of electronic switching electric motorscurrently in use for activating ventilation devices, electric motors ofthe kind mentioned above present a high level of operating efficiencyand a low level of consumption, and, taking into consideration that thedemand for electric motors for activating ventilation devices is in theorder of hundreds of thousands of units per year, the use of electronicswitching electric motors for these kind of applications means thatconsiderable savings in financial terms can be made.

It should be stated, however, that the electronic switching electricmotors currently in use still have a relatively complex structure, tothe extent that the achievement of the above-mentioned savings infinancial terms is somewhat compromised.

The aim of the present invention is to realise an electronic switchingelectric motor which can be used for the activation of ventilationdevices in refrigerators, which is economically viable and simple toproduce.

According to the present invention, an electronic switching electricmotor is to be realised comprising a rotor, and a stator defined by anumber of stator teeth and by an assembly element of the stator teeththemselves; the electric motor being characterised by the fact that thesaid assembly element comprises two support seats for the rotor, atleast a first seat of the said two seats being realised with theassembly element itself.

The invention will now be described with reference to the attacheddrawings, which illustrate a non-limiting embodiment of the invention,in which:

FIG. 1 illustrates a first preferred embodiment of an electric motor,according to the present invention, in section;

FIG. 2 illustrates a transverse section, with some parts removed forreasons of clarity, of the motor shown in FIG. 1;

FIG. 3 illustrates, on a reduced scale and with some parts in sectionand some parts removed for reasons of clarity, a second preferredembodiment of the electric motor shown in FIG. 1;

FIG. 4 illustrates, on a reduced scale and with some parts in sectionand some parts removed for reasons of clarity, a third preferredembodiment of the electric motor shown in FIG. 1;

FIG. 5 illustrates a preferred form of embodiment of a detail of themotor shown in FIG. 1; and

FIG. 6 illustrates a frontal elevation of a detail of FIG. 5.

With reference to FIGS. 1 and 2, the number 1 indicates, in itsentirety, an electronic switching electric motor suitable for activatinga ventilation device 2 which can be installed in a refrigerator (notillustrated).

The motor 1 is a brush-less motor with four-pole permanent magnets,supplied by mains voltage (50÷60 Hz; 110÷230 V), and it comprises anexternal casing 3 for protection and support, a rotor 4, a stator 5supported by the casing 3 itself and presenting an internal opening 6for housing the rotor 4, and an electronic device 7 for supplying andcontrolling the motor 1 itself lined with a protective layer ofinsulating resin.

The rotor 4 comprises a shaft 8, which is rotatably supported by thestator 5 by means of the interposition of two bushings 9, and presents afree extremity 10 which extends to the exterior of the opening 6 and tothe exterior of the casing 3 to support an axial fan 11 of the device 2.The rotor 4 also comprises a permanent magnet 12, which is placed insidethe opening 6, and mounted on the shaft 8 in an intermediate positionbetween the bushings 9 and is angularly integral to the shaft 8 itself.

The stator 5 comprises four stator teeth 13, which are uniformlydistributed around an A axis of rotation of the rotor 4, and are eachdefined by a number of shaped metallic laminations 14 laterally arrangedside by side one to the other. The stator 5 also comprises an assemblyelement 15 of the teeth 13, and an external ring 16, which rigidly joinsthe teeth 13 to each other, but this is mounted on the teeth 13 onlyafter the realisation of the stator windings 17. The element 15 is amonolithic element realised in plastic material co-molded with the teeth13, and comprising a main tubular body 18 coaxial to the A axis, and foreach tooth 13, a secondary tubular body 19, which is transversallyarranged to the A axis itself, and is provided with, in correspondenceto a radially external extremity 20, a flange 21. The flange 21 defines,with the relative body 19 and with the body 18, a reel 22 provided withan annular seat 22 a, which houses a relative winding 17, and isaccessible form the outside due to the realisation of the winding 17itself, for example by means of a so-called flyer, until the ring 16 ismounted onto the teeth 13.

The element 15 also comprises two longitudinal extremity portions 23 and24 arranged on either side of the body 18, and of which the portion 23is facing towards the fan 11, and this is a tubular portion providedwith an annular border 25 transverse to the A axis, while the portion 24is substantially T-shaped, and comprises a disc 26 arrangedtransversally to the A axis and joined to the body 18, and a cylinder 27which extends along the A axis from the disc 26 opposite the opening 6with regard to the disc 26 itself.

The element 15 also finally comprises a cover 28, which is coupled tothe border 25 to close the section 6, and presents a through hole 29co-axial to the A axis, and rotatably engaged by the shaft 8. Inparticular, the cover 28 comprises a circular plate 30 presenting anexternal annular border 30 mounted with interference inside the border25; and a tubular element 32 which extends along the A axis from theplate 30 opposite the section 6 with regard to the plate 30 itself.

The disc 26 and the plate 30 are both provided with two support seats33, each of which houses a relative bushing 9, and presents, on the partturned towards the opening 6, an opening 34 which permits the relativebushing 9 to be snap mounted. The disc 26 is also provided, on the partturned towards the exterior of the opening 6, with a number of fixingelements 35 for fixing the device 7 to the disc 26 itself, and with adetermined number of anchor pins 36 for the winding wires whichco-operate with the element 35 for fixing the device 7 itself.

The casing 3 comprises two semi-shells 37 and 38 jointed and assembledto each other, of which the shell 37 presents a hole 39 co-axial to theA axis and an annular border 40 which extends around the hole 39 itself,while the shell 38 is provided with two external support flanges 42suitable for permitting the casing 3 to be mounted on a rigid support(not illustrated) of the above-mentioned refrigerator, and presenting ahole 42 which is rotatable engaged by the extremity 10 of the shaft 8,and an annular border 43 which extends around the hole 42 itself.

The casing 3 also comprises two elastic support elements 44, which aredefined by respective rings preferably realised in elastomer, areinterposed between the border 40 and the cylinder 27 and between theborder 43 and the tubular element 32, and are suitable for elasticallysuspending the motor 1 and insulating it form the vibrations caused bythe pulsating of the torque and the unbalancing of the rotor 4. Thepresence of the elements 44 permits the installation of the motor 1 onany kind of rigid support without needing to provide any further elasticsupports and thus permits not only the reduction of installation timebut also the uniform performance of the motor 1 itself.

The embodiment illustrated in FIG. 3 shows an motor 51 like the motor 1,except that the motor 51 differs from the motor 1 due to the fact thatthe assembly element 15 is not monolithic but instead comprises twoassembly semi-elements 52 and 53, which are realised in molded plasticmaterial, and these are assembled with the stator 5 before therealisation of the windings 17, and anyway before the rotor 4 ispartially inserted into the opening 6. The semi-element 53 presents arelative support seat 33 engaged by a relative bushing 9, while theother seat 33 is still obtained in the cover 28.

The embodiment illustrated in FIG. 4 shows an motor 61 like the motor51, except for the fact that the motor 61 differs from the motor 51 dueto the fact that the cover 28 is realised by means of being moldedtogether with the semi- element 52 so that the border 31 of the plate 30is joined to the annular border 25 of the cylinder 18. In this case, thesemi-elements 52 and 53 are assembled to each other after the rotor 4has been partially inserted into the opening 6, and before therealisation of the windings 17. In this case, the seats 22 are obtainedin each semi-element 52 and 53, and the relative bushings 9 are snapmounted in the seats 33 before the two semi-elements 52 and 53 areassembled to each other.

FIGS. 5 and 6 illustrate a preferred embodiment of the elastic supportelements 44, which is to say that they illustrate two elastic supportelements 71 (of which only one is shown), which, instead of beingdefined by respective rings which can be mounted inside the borders 40and 43, are realised integrally with the relative semi-shells 37 and 38,and comprise, in place of the borders 40 and 43 themselves, a respectiveexternal annular plate 72 and a respective internal annular plate 73which are co-axial to each other and to the A axis. Each element 71 alsocomprises at least two springs 74 for connecting the relative plates 72and 73 suitable for permitting both the movement of the motor shaft 8 ina transverse direction to the A axis and the rotation of the plate 73 inrelation to the relative plate 72, and suitable for contrasting anymovement of the shaft 8 itself in an axial direction parallel to the Aaxis. The springs 74 with which each element 71 is provided can also beprovided for in a greater number than that shown in the illustration,for example in the case that it is necessary to increase the rigidity ofthe element 71 itself.

It is evident form the above description that the motor 1, in thepreferred embodiment described, achieves the aims of minimising bothassembly time, by using internal components in the place of furtherexternal components for coupling to the above-mentioned rigid support,and production casts by realising the assembly element 15 and the casing3 in such a way as to save on the costs of components for assembly andmounting. It is also possible to have an electric motor 1 ready to beinstalled without the addition, as mentioned above, of any furtherexternal components, permitting uniform performance according to theparameters projected for the motor 1 itself.

What is claimed:
 1. Electronic switching electric motor comprising arotor, a stator defined by a number of stator teeth and by an assemblyelement of the stator teeth, and an external casing and two elasticsupports interposed between the assembly element and the externalcasing; wherein the assembly element comprises two support seats for therotor, at least a first seat of the tow seats being located within theassembly element; the assembly element presenting an internal openingfor the rotor, the assembly element further comprising a cover forclosing the internal opening; a second seat of the two seats beinglocated within the cover; wherein the assembly element is made form aninsulating plastic and is co-molded together with the stator teeth. 2.Motor according to claim 1, wherein the assembly element compriseshousing and fixing means for housing the cover and for fixing the coverto the assembly element.
 3. Motor according to claim 1, wherein theassembly element comprises two semi-elements for assembly, molded andassembled to each other.
 4. Motor according to claim 3, wherein one ofthe two semi-elements comprises housing means for housing the cover andfor fixing the cover to the semi-element for assembly.
 5. Motoraccording to claim 4, wherein each of the semi-elements for assemblycomprise a relative support seat for the rotor.
 6. Motor according toclaim 5, wherein the cover is integral with one of the two semi-elementsfor assembly.
 7. Motor according to claim 1, wherein the two elasticsupports are integral with the external casing.
 8. Motor according toclaim 1, wherein the external casing comprises at least one flange forcoupling the external casing to a rigid support.
 9. Motor according toclaim 1, wherein the rotor is angularly coupled to a fan fo aventilation device for refrigerators.
 10. Motor according to claim 1,wherein the two support seats comprise relative support bushings for therotor which can be snap mounted inside the support seats.
 11. Motoraccording to claim 1, the motor further comprising an electronic devicefor supplying and controlling the electric motor.